Detect to defend: the assortment of viral diagnostic techniques


Now, when we are trying to cope with the new normal, there are scientists working day-in and day-out to revert it back to the good-old normal!


Ages before the COVID-19 outbreak, our lives were tumbled by these microscopic beasts, many a time. Be it a common cold or seasonal flu or other severe forms like HIV, Ebola or Smallpox. It has been a continuous challenge to ward them off, right from detection to cure.


Viral diagnostics is the talk of the town.


Early and successful viral detection can limit the feast of pandemics. In this piece, we will explore the novel detection techniques and understand the future of the field.



Microfluidics: micro answers to macro problems


Microfluidics technology offers tools that allow the defined control and operation of fluids in small quantities (microlitre to picolitre range) — a multidisciplinary field connecting physics, biochemistry, nanotechnology, and engineering. It is a booming application across healthcare and pharmaceutical spheres.


In a typical microfluidic chip, a minuscule amount of fluid is injected in microscopic channels requiring the negligible amount of samples and reagent, ensuring superior proficiency at a lower cost compared with many other conventional approaches.


The lab of Pavel Neužil at CEITEC BUT enriches the field of microfluidics.




A microfluidic chip (source: www.futurity.org)



With more than 100 publications and 10 patents under his name, Dr Neužil is interested in economic, straightforward and portable systems for point-of-care (POC) diagnostics employing molecular methods.

POC diagnostics (also known as bedside testing) involves testing right at or near the place of patient care.

In a recent article (1), Neužil and fellow researchers have assembled the current knowledge of a specific form of the POC diagnostic scheme, the lab-on-a-chip (LOC) devices.




Dr Pavel Neužil (source: en.lzu.edu.cn)




The LOC devices


Imagine a laboratory (or several of them) on a single chip, of a diameter of the 10th of your hair!

They can integrate the function of several laboratories achieving high-throughput screening and automation, without the need for their physical presence.


Conventional methods for the diagnosis of viral diseases are typically based on virus-infected cell cultures or the detection of viral antigens, antibodies, and nucleic acids, which are labour-intensive and time-consuming techniques, Dr Neužil says.


He adds, the trend of miniaturisation, cost-effectiveness and rapid viral monitoring via LOC-based means is irrefutably a global public health ambition.





Lab-on-a-chip (source: www.gene-quantification.de)




The voyage of LOC-based viral detection



  • Microfluidic immunoassays


Immunoassays make use of the sensitivity and specificity of the antibody-antigen interactions, allowing monitoring of small molecules, and even pathogens.

Miniaturised immunofluorescence assays on the 3D-printed bead-based microfluidic chips are currently widely used for viral detection.

The beads are coated with antibodies that can detect specific viral particles, for instance, the 5-min rapid detection of dengue virus (2) using a dielectrophoresis chip, or the automated magnetic bead-based microfluidic enzyme-linked immunosorbent assay (ELISA) to detect HIV (3).





A flow-free magnetic actuation platform for microfluidic ELISA test (3)



  • Microfluidic detection of nucleic acids


Amongst the molecular diagnostic methods, nucleic acid (NA)-based techniques play an essential role in accurate and selective viral identification. NA detection involves three parts; sample preparation, NA amplification, and result detection – all can be integrated on a chip.


The authors mentioned: Compared with bulky benchtop equipment, microfluidic devices possess the advantages of portability and low sample and time consumption, indicating potential application in POC systems.


Dr Neužil and fellow researchers have previously fabricated devices for the real-time detection of NA. An integrated real-time hand-held system is one of the examples, to detect RNA of H5N1 avian influenza virus using real-time RT-PCR (4).





PCR chip with the optical housing underneath (4)



Another portable device was applied to provide an internet of things (IoT) platform for diagnosis of dengue virus.


The IoT offers a magnificent opportunity, where the retrieved data was automatically uploaded via a Bluetooth interface to an Android-based smartphone and then wirelessly sent to a global network; making it instantly accessible from anywhere in the world.





Optic design of integrated real-time fluorescence detector (5)




The current trends and future prospective


The COVID-19 pandemic has resurfaced several LOC devices in the market when rapid testing has become a colloquial phrase and development of many other new devices have accelerated in the last months (6).


According to the authors, the smartphone platforms will be utilised, taking advantage of the high-resolution cameras forming IoT (5). The test results can be directly disseminated to medical personnel or health centres monitoring the infectious disease practically immediately once the test in the point of care is completed.


Dr Neužil and colleagues state the importance of this innovation, the LOC technology for POC assays is moving towards speed and efficiency in the diagnosis of viral diseases. Portability, cost, automation, speed, efficiency, and connectivity are crucial technical parameters for the future generation of LOCs in viral disease diagnosis.



References

  1. Zhu H, Fohlerova Z, Pekárek J, Basova E, Neužil P (2020) Recent advances in lab‐on‐a‐chip technologies for viral diagnosis. Biosensors and Bioelectronics 153, 112041.
  2. Iswardy, E., Tsai, T.C., Cheng, I.F., Ho, T.C., Perng, G.C., Chang, H.C., 2017. A bead-based immunofluorescence-assay on a microfluidic dielectrophoresis platform for rapid dengue virus detection. Biosens. Bioelectron. 95, 174–180
  3. Coarsey, C., Coleman, B., Kabir, M.A., Sher, M., Asghar, W., 2019. Development of a flow-free magnetic actuation platform for an automated microfluidic ELISA. RSC Adv. 9 (15), 8159–8168
  4. Neuzil, P., Novak, L., Pipper, J., Lee, S., Ng, L.F.P., Zhang, C., 2010. Rapid detection of viral RNA by a pocket-size real-time PCR system. Lab Chip 10 (19), 2632–2634
  5. Zhu, H., Podesva, P., Liu, X., Zhang, H., Teply, T., Xu, Y., Chang, H., Qian, A., Lei, Y., Li, Y., et al. 2020. IoT PCR for pandemic disease detection and its spread monitoring. Sensor. Actuator. B Chem. 303, 1–7.
  6. https://www.fierceelectronics.com/electronics/ams-ag-accurate-coronavirus-test-results-minutes-a-life-saving-new-application-chip



Written by Somsuvro Basu


Publication date: 21.08.2020